1. Field of the Invention
The present invention relates to a housing for a magnetic disk drive of the type which is subdivided into a cover and into a supporting shell in which a disk pack is seated rotatably at both ends and in which a magnetic head positioner device is disposed, whereby a seal between the supporting shell and the cover provides a dust-free sealing of the housing interior and whereby one of the bearings for the disk pack in a lateral wall of the supporting shell is designed as a slot open toward the edge of the supporting shell for receiving a corresponding disk pack bearing.
2. Description of the Prior Art
Technical development in magnetic disk drives continues to constantly work towards higher and higher storage capacities, both with respect to the track density and the bit density as characteristic for the storage capacity per disk surface, on the one hand, and with respect to the mechanical structure, on the other hand, in order to accommodate as many magnetic disks as possible in a prescribed mounting space. An example of this is the so-called 51/4" fixed disk memory whose magnetic disks have an outer diameter of 130 mm and an inner diameter of 40 mm according to the German Industrial Standard. Analogous to the dimensions of the competing floppy disk drives, a mounting space having a mounting height of 82.5 mm and a base area of 146 mm.times.203 mm has crystallized as a standard unit size for this type of memory, being available for the entire device including the housing and the appertaining electronics.
In the desire to accommodate as many magnetic disks as possible in this prescribed mounting space, the drive motor for the disk pack has been successfully miniaturized to such a degree that it can be built into the hub of the disk pack. With the useable mounting height thereby gained, disk packs which contain up to eight magnetic disks stacked on top of one another have become possible based on the current conditions in the size of the combined magnetic heads and the disk thickness. The remaining mounting height is required for the housing and the device electronics.
The desired compact structure and the desired high recording density on the magnetic disks produce special structural measures in order to achieve justifiable manufacturing costs given sufficient operating reliability, but also to achieve a desired accessibility of the disk pack and of the appertaining magnetic head positioner upon assembly and in a test mode.
To this end, the housing of the magnetic disk drive in the present case is divided along a parting plane parallel to the central axis of the disk pack and of the magnetic head positioner, being divided into a tub-like supporting shell and a cover such that both bearing locations for the disk pack lie just within the lateral walls of the supporting shell. However, in order to maintain the mounting depth of the magnetic head positioner into the supporting shell as small as possible, the parting plane is inclined at an angle relative to the end wall of the supporting shell. The magnetic head positioner, which is designed as a rotational positioner, is secured to the inside of the wall of the supporting shell and is mounted in the housing as a completely tested module. The same is true of the disk pack. In order to enable the foregoing, a slot open up to the edge of the supporting shell is provided in one of the lateral walls and the allocated spindle peg of the disk pack is received in the slot during assembly. The other spindle peg is fixed at the opposite end wall of the supporting shell by a screw connection which extends through the housing wall.
The structural format enables a step-by-step assembly of the modules and, assuming a dust-free environment, allows a test mode of the magnetic disk drive, even given a removed cover, and simultaneously allows a far-reaching accessibility of the individual modules in this condition.
The operating reliability of magnetic disk drives also largely depends on the hermetic seal of the housing interior in which the disk pack rotates from disturbing influences of the environment. Due to the sensitivity of the surface of the magnetic disks and particularly to the slight spacings at which the magnetic heads of the rotational positioner fly above the surfaces of the allocated magnetic disks during operation, it is, absolutely necessary that any and all influence of dust from the exterior be avoided.